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Lennox G14Q4 problem - long delay before blower starts, no heat until it starts

Lennox G14Q4 problem - long delay before blower starts, no heat until it starts

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  #1  
Old 04-01-12, 11:13 PM
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Lennox G14Q4 problem - long delay before blower starts, no heat until it starts

If I run the fan/blower continuously, the furnace cycles on and off normally. However, if I put the blower setting on auto, once the furnace completes a cycle and reaches the set temperature, (and the blower shuts down), the furnace will not cycle back on when the temperature drops. It will restart if I shut the furnace off and switch the blower/fan setting back to continuous. However, it takes a good 5 to 10 minutes for the blower to start. Once the blower starts and I switch the furnace back on, the furnace fires up immediately.

I'm guessing that this involves the indoor blower relay...or could it be something else?

Any advice would be appreciated. I think it's been over a year since last servicing.

Mike H
 
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  #2  
Old 04-02-12, 12:02 PM
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I would first check the thermostat. Is it getting voltage from the furnace? Sending a signal on a call for heat? What is the temperature differential set at?
 
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Old 04-02-12, 05:47 PM
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Per chance is this furnace equipped with a Johnson ignition module. Such as a G67 or G76 series blue and grey colors
 
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Old 04-03-12, 12:47 AM
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Originally Posted by goldstar View Post
I would first check the thermostat. Is it getting voltage from the furnace? Sending a signal on a call for heat? What is the temperature differential set at?
Well, haven't tried a DMM yet. But this is what happened tonight:

Temperature reaches trigger point (>.75 degrees difference)

The blower setting was on automatic and the temperature had dropped below the trigger point. I heard a humming noise from furnace which lasted for > 10 minutes, then it shut down. The blower never turned on, but the exit duct work right above furnace warmed up.

I then switched the blower setting to continuous. I heard a softer humming sound from furnace, but the duct above the furnace did not heat up. The blower came on after about 10 minutes. The furnace now turns off and on normally as temperature varies.

Does this give you any more information, or do I need to drag out the multimeter and try to figure out how and where to read the voltage?

Thanks

Mike H
 
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Old 04-03-12, 12:54 AM
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Originally Posted by mbk3 View Post
Per chance is this furnace equipped with a Johnson ignition module. Such as a G67 or G76 series blue and grey colors
Havn't opened up the panel yet. I'll try looking inside tomorrow. I'ts a little late tonight.
 
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Old 04-04-12, 11:21 PM
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The G14 is an older pulse furnace.

Get it checked by a lennox dealer.
 
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